Sub-Sampling Receiver

1. A wireless signal receiver comprising: an analog-digital converter (ADC) configured to convert an analog radio frequency (RF) signal into a digital baseband signal; and a sub-sampling block configured to generate a first path signal and a second path signal from the digital baseband signal, and configured to extract a complex baseband signal by using a relative sample delay difference between the first and second path signals, wherein the sub-sampling block comprises: a sampling rate up-converter configured to up-convert a sampling rate of the digital baseband signal; a sample delay unit configured to sample delay an output of the sampling rate up-converter; and a sampling rate down-converter configured to down-convert a sampling rate of an output from the sample delay unit to output as the first path signal; wherein the sub-sampling block is configured to generate the first path signal by applying the sample delay and the sampling rate conversion to the digital baseband signal and to generate the second path signal without adjusting the sampling rate of the digital baseband signal.

2. The wireless signal receiver of claim 1 , wherein the sub-sampling block further comprises: a first digital filter configured to filter the first path signal; a second digital filter configured to filter the second path signal; and an adder configured to add a filtering result of the first digital filter to a filtering result of the second digital filter, and to output the result of the adder as the complex baseband signal.

3. The wireless signal receiver of claim 2 , wherein the adder comprises a subtractor configured to subtract the filtering result of the second digital filter from the filtering result of the first digital filter, and to output the result of the subtractor as the complex baseband signal.

4. The wireless signal receiver of claim 2 , wherein the relative sample delay difference between the first path signal and the second path signal is determined by at least one of: a sampling rate of the ADC, a delay size of the sample delay unit, and sampling conversion rates of the sampling rate up-converter and the sampling rate down-converter.

5. The wireless signal receiver of claim 2 , wherein respective filter coefficients of the first digital filter and the second digital filter are determined by at least one of: a carrier frequency of the analog RF signal, a frequency band location index of the analog RF signal, a sampling rate of the ADC, a delay size of the sample delay unit, and a conversion ratio N of the samplinq rate down-converter.

6. The wireless signal receiver of claim 5 , wherein the sampling rate f s , the delay size D of the sample delay unit, and the sample conversion ratio N of the samplinq rate down-converter are set to satisfy the relationship 2nD/N ≠ m, wherein n is a frequency band location index of the analog RF signal, and m is an integer.

7. The wireless signal receiver of claim 2 , wherein the first digital filter and the second digital filter are determined to satisfy at least one of: S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R + ⁡ ( f ) , Equations S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R + ⁡ ( f ) , Equations S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R - ⁡ ( f ) ⁢ ⁢ and Equations S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R - ⁡ ( f ) , Equations wherein S(f) is a spectrum of an output signal of the adder, S A δ (f) corresponds to a spectrum of an output signal of the first digital filter, S B δ (f) corresponds to a spectrum of an output signal of the second digital filter, R_(f) corresponds to a negative frequency spectrum of the digital baseband signal, and R + (f) corresponds to a positive frequency spectrum of the digital baseband signal.

8. The wireless signal receiver of claim 2 , wherein the second digital filter comprises a complex multiplier configured to amplify the digital baseband signal, to a gain having a certain size.

9. The wireless signal receiver of claim 8 , further comprising: a synchronous delay unit configured to delay the digital baseband signal by a specific delay time to provide to the complex multiplier.

10. A wireless signal receiver comprising: an analog-digital converter (ADC) configured to convert an analog radio frequency (RF) signal into a digital baseband signal; and a sub-sampling block configured to generate a first path signal and a second path signal from the digital baseband signal, and configured to extract a complex baseband signal by using a relative sample delay difference between the first and second path signals, wherein the sub-sampling block comprises: a sample delay unit configured to sample delay the digital baseband signal, on at least one sample basis, and a first sampling rate converter configured to change a sampling rate of an output from the sample delay unit to provide a fractional delay effect to the first path signal, and to output the result of the first sampling rate converter as the first path signal; wherein the sub-sampling block is configured to generate a first path signal by applying the sample delay and the sampling rate conversion to the digital baseband signal, and to generate the second path signal by adjusting a sampling rate of the digital baseband signal without a sample delay of the digital baseband signal.

11. The wireless signal receiver of claim 10 , wherein the sub-sampling block further comprises: a first digital filter configured to filter the first path signal; a second sampling rate converter configured to change a sampling rate of the digital baseband signal, and to output the result of the second sampling rate converter as the second path signal; a second digital filter configured to filter the second path signal; and an adder configured to add a filtering result of the first digital filter to a filtering result of the second digital filter, and to output the result of the adder as the complex baseband signal.

12. The wireless signal receiver of claim 11 , wherein the adder comprises a subtractor configured to subtract the filtering result of the second digital filter from the filtering result of the first digital filter, and to output the result of the subtractor as the complex baseband signal.

13. The wireless signal receiver of claim 11 , wherein the relative delay difference between the first path signal and the second path signal is determined by at least one of: a sampling rate of the ADC, a delay size of the sample delay unit, and sampling conversion rates of the first sampling rate converter and the second sampling rate converter.

14. The wireless signal receiver of claim 11 , wherein respective filter coefficients of the first digital filter and the second digital filter are determined by at least one of: a carrier frequency of the analog RF signal, a frequency band location index of the analog RF signal, a sampling rate of the ADC, a delay size of the sample delay unit, and a conversion ratio L/M of the first sampling rate converter to the second sampling rate converter.

15. The wireless signal receiver of claim 14 , wherein the sampling rate f s , a delay size D of the sample delay unit, and the sample conversion ratio L/M of the first sampling rate converter and the second sampling rate converter are set to satisfy the relationship 2nLD/M ≠ m, wherein n is a frequency band location index of the analog RF signal, and m is an integer.

16. The wireless signal receiver of claim 11 , wherein the first digital filter and the second digital filter are determined to satisfy at least one of: S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R + ⁡ ( f ) , Equations S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R + ⁡ ( f ) , Equations S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R - ⁡ ( f ) , ⁢ ⁢ and Equations S ⁡ ( f ) = ⁢ S A δ ⁡ ( f ) + S B δ ⁡ ( f ) = ⁢ R - ⁡ ( f ) , Equation wherein S(f) is a spectrum of an output signal of the adder, S A δ (f) corresponds to a spectrum of an output signal of the first digital filter, S B δ (f) corresponds to a spectrum of an output signal of the second digital filter, R − (f) corresponds to a negative frequency spectrum of the digital baseband signal, and R + (f) corresponds to a positive frequency spectrum of the digital baseband signal.

17. The wireless signal receiver of claim 11 , wherein the second digital filter comprises a complex multiplier configured to amplify the second path signal by a gain having a certain size.

18. The wireless signal receiver of claim 17 , further comprising: a synchronous delay unit configured to delay the second path signal by a specific delay time to provide to the complex multiplier.

19. The wireless signal receiver of claim 2 , wherein the second path signal is a signal obtained without applying sampling delay.

20. A wireless signal receiver comprising: an analog-digital converter (ADC) configured to convert an analog radio frequency (RF) signal into a digital baseband signal; and a sub-sampling block configured to divide and process the digital baseband signal into a first path signal and a second path signal, and configured to divide and process a complex baseband signal, by using a relative sample delay difference between the first and second path signals, wherein the sub-sampling block comprises: a first sampling rate converter configured to change the sampling rate of the digital baseband signal, a sample delay unit configured to sample delay an output of the first sampling rate converter, on at least one sample basis, and a second sampling rate converter configured to change a sampling rate of an output from the sample delay unit to output as the first path signal; wherein the sub-sampling block is configured to obtain the first path signal by adjusting the sample delay and the sampling rate of the digital baseband signal, and to obtain the second path signal without adjusting a sampling rate of the digital baseband signal.